Macarthur police Senior Constable David Rook said he clocked the 21-year-old from western South Australia about 8.30pm on Sunday  along the Port Fairy-Hamilton Road.

The driver was checked at a speed of 139km/h, returned a positive preliminary breath test and later an evidentiary reading of .105.

The 21-year-old has lost his licence for 10 months and has been fined about $1200.

Senior Constable Rook said an aggravating feature of the driving was that the man was subject to a zero alcohol condition as he was a probationary driver.

"He shouldn't be drinking any alcohol and driving," he said.

"This was a recipe for disaster. The combination of speed and alcohol is potentially deadly.

"I was quite staggered that the driver had been drinking anything."

In unrelated police news, Senior Constable Rook said  an expensive ladder had been found on the side of the Warrnambool-Caramut Road, near the turnoff to Woodford.

The owner of the ladder is requested to contact the Macarthur police station.